This relates generally to image sensors, and more specifically, to the capture and adjustment of transient signals within image sensors, particularly those below the ground reference voltage or above the supply voltage.
Image sensors are commonly used in electronic devices such as cellular telephones, cameras, and computers to capture images. In a typical arrangement, an electronic device with an image sensor is provided with an array of image sensor pixels arranged in pixel rows and columns. Column sensing circuitry is typically coupled to each pixel column for reading out image signals from the image pixels.
Conventional image sensors often perform imaging by amplifying pixel control signals using a voltage boost which adjusts the original signal either below the ground reference voltage or above the operating voltage supply of the image sensor. The voltage boost is typically provided by one or more pixel control circuits coupled to the image sensor pixel array.
In practice, if one of the pixel control circuits that provides the voltage boost were to fail or have degraded performance, there would be no indication of the failure other than resultant dim or low dynamic range and image artifacts in the final image produced by the image sensor. In some applications where the quality of a produced image may affect the safety of the device or the user, such an unexpected failure or degradation in sensor performance could be catastrophic.
It would therefore be desirable to be able to provide imaging systems and methods with improved capabilities for monitoring and verifying the integrity of transient voltage signals in the image sensor in real-time.